1 /* -*- c -*- --------------------------------------------------------------- *
2 *
3 * linux/fs/autofs/root.c
4 *
5 * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
6 * Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
7 *
8 * This file is part of the Linux kernel and is made available under
9 * the terms of the GNU General Public License, version 2, or at your
10 * option, any later version, incorporated herein by reference.
11 *
12 * ------------------------------------------------------------------------- */
13
14 #include <linux/errno.h>
15 #include <linux/stat.h>
16 #include <linux/param.h>
17 #include <linux/sched.h>
18 #include <linux/smp_lock.h>
19 #include "autofs_i.h"
20
21 static struct dentry *autofs4_dir_lookup(struct inode *,struct dentry *);
22 static int autofs4_dir_symlink(struct inode *,struct dentry *,const char *);
23 static int autofs4_dir_unlink(struct inode *,struct dentry *);
24 static int autofs4_dir_rmdir(struct inode *,struct dentry *);
25 static int autofs4_dir_mkdir(struct inode *,struct dentry *,int);
26 static int autofs4_root_ioctl(struct inode *, struct file *,unsigned int,unsigned long);
27 static struct dentry *autofs4_root_lookup(struct inode *,struct dentry *);
28
29 struct file_operations autofs4_root_operations = {
30 read: generic_read_dir,
31 readdir: dcache_readdir,
32 ioctl: autofs4_root_ioctl,
33 };
34
35 struct file_operations autofs4_dir_operations = {
36 read: generic_read_dir,
37 readdir: dcache_readdir,
38 };
39
40 struct inode_operations autofs4_root_inode_operations = {
41 lookup: autofs4_root_lookup,
42 unlink: autofs4_dir_unlink,
43 symlink: autofs4_dir_symlink,
44 mkdir: autofs4_dir_mkdir,
45 rmdir: autofs4_dir_rmdir,
46 };
47
48 struct inode_operations autofs4_dir_inode_operations = {
49 lookup: autofs4_dir_lookup,
50 unlink: autofs4_dir_unlink,
51 symlink: autofs4_dir_symlink,
52 mkdir: autofs4_dir_mkdir,
53 rmdir: autofs4_dir_rmdir,
54 };
55
56 /* Update usage from here to top of tree, so that scan of
57 top-level directories will give a useful result */
58 static void autofs4_update_usage(struct dentry *dentry)
59 {
60 struct dentry *top = dentry->d_sb->s_root;
61
62 for(; dentry != top; dentry = dentry->d_parent) {
63 struct autofs_info *ino = autofs4_dentry_ino(dentry);
64
65 if (ino) {
66 update_atime(dentry->d_inode);
67 ino->last_used = jiffies;
68 }
69 }
70 }
71
72 static int try_to_fill_dentry(struct dentry *dentry,
73 struct super_block *sb,
74 struct autofs_sb_info *sbi)
75 {
76 struct autofs_info *de_info = autofs4_dentry_ino(dentry);
77 int status = 0;
78
79 /* Block on any pending expiry here; invalidate the dentry
80 when expiration is done to trigger mount request with a new
81 dentry */
82 if (de_info && (de_info->flags & AUTOFS_INF_EXPIRING)) {
83 DPRINTK(("try_to_fill_entry: waiting for expire %p name=%.*s, flags&PENDING=%s de_info=%p de_info->flags=%x\n",
84 dentry, dentry->d_name.len, dentry->d_name.name,
85 dentry->d_flags & DCACHE_AUTOFS_PENDING?"t":"f",
86 de_info, de_info?de_info->flags:0));
87 status = autofs4_wait(sbi, &dentry->d_name, NFY_NONE);
88
89 DPRINTK(("try_to_fill_entry: expire done status=%d\n", status));
90
91 return 0;
92 }
93
94 DPRINTK(("try_to_fill_entry: dentry=%p %.*s ino=%p\n",
95 dentry, dentry->d_name.len, dentry->d_name.name, dentry->d_inode));
96
97 /* Wait for a pending mount, triggering one if there isn't one already */
98 while(dentry->d_inode == NULL) {
99 DPRINTK(("try_to_fill_entry: waiting for mount name=%.*s, de_info=%p de_info->flags=%x\n",
100 dentry->d_name.len, dentry->d_name.name,
101 de_info, de_info?de_info->flags:0));
102 status = autofs4_wait(sbi, &dentry->d_name, NFY_MOUNT);
103
104 DPRINTK(("try_to_fill_entry: mount done status=%d\n", status));
105
106 if (status && dentry->d_inode)
107 return 0; /* Try to get the kernel to invalidate this dentry */
108
109 /* Turn this into a real negative dentry? */
110 if (status == -ENOENT) {
111 dentry->d_time = jiffies + AUTOFS_NEGATIVE_TIMEOUT;
112 dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
113 return 1;
114 } else if (status) {
115 /* Return a negative dentry, but leave it "pending" */
116 return 1;
117 }
118 }
119
120 /* If this is an unused directory that isn't a mount point,
121 bitch at the daemon and fix it in user space */
122 spin_lock(&dcache_lock);
123 if (S_ISDIR(dentry->d_inode->i_mode) &&
124 !d_mountpoint(dentry) &&
125 list_empty(&dentry->d_subdirs)) {
126 DPRINTK(("try_to_fill_entry: mounting existing dir\n"));
127 spin_unlock(&dcache_lock);
128 return autofs4_wait(sbi, &dentry->d_name, NFY_MOUNT) == 0;
129 }
130 spin_unlock(&dcache_lock);
131
132 /* We don't update the usages for the autofs daemon itself, this
133 is necessary for recursive autofs mounts */
134 if (!autofs4_oz_mode(sbi))
135 autofs4_update_usage(dentry);
136
137 dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
138 return 1;
139 }
140
141
142 /*
143 * Revalidate is called on every cache lookup. Some of those
144 * cache lookups may actually happen while the dentry is not
145 * yet completely filled in, and revalidate has to delay such
146 * lookups..
147 */
148 static int autofs4_root_revalidate(struct dentry * dentry, int flags)
149 {
150 struct inode * dir = dentry->d_parent->d_inode;
151 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
152 struct autofs_info *ino;
153 int oz_mode = autofs4_oz_mode(sbi);
154
155 /* Pending dentry */
156 if (autofs4_ispending(dentry)) {
157 if (autofs4_oz_mode(sbi))
158 return 1;
159 else
160 return try_to_fill_dentry(dentry, dir->i_sb, sbi);
161 }
162
163 /* Negative dentry.. invalidate if "old" */
164 if (dentry->d_inode == NULL)
165 return (dentry->d_time - jiffies <= AUTOFS_NEGATIVE_TIMEOUT);
166
167 ino = autofs4_dentry_ino(dentry);
168
169 /* Check for a non-mountpoint directory with no contents */
170 spin_lock(&dcache_lock);
171 if (S_ISDIR(dentry->d_inode->i_mode) &&
172 !d_mountpoint(dentry) &&
173 list_empty(&dentry->d_subdirs)) {
174 DPRINTK(("autofs_root_revalidate: dentry=%p %.*s, emptydir\n",
175 dentry, dentry->d_name.len, dentry->d_name.name));
176 spin_unlock(&dcache_lock);
177 if (oz_mode)
178 return 1;
179 else
180 return try_to_fill_dentry(dentry, dir->i_sb, sbi);
181 }
182 spin_unlock(&dcache_lock);
183
184 /* Update the usage list */
185 if (!oz_mode)
186 autofs4_update_usage(dentry);
187
188 return 1;
189 }
190
191 static int autofs4_revalidate(struct dentry *dentry, int flags)
192 {
193 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
194
195 if (!autofs4_oz_mode(sbi))
196 autofs4_update_usage(dentry);
197
198 return 1;
199 }
200
201 static void autofs4_dentry_release(struct dentry *de)
202 {
203 struct autofs_info *inf;
204
205 lock_kernel();
206
207 DPRINTK(("autofs4_dentry_release: releasing %p\n", de));
208
209 inf = autofs4_dentry_ino(de);
210 de->d_fsdata = NULL;
211
212 if (inf) {
213 inf->dentry = NULL;
214 inf->inode = NULL;
215
216 autofs4_free_ino(inf);
217 }
218
219 unlock_kernel();
220 }
221
222 /* For dentries of directories in the root dir */
223 static struct dentry_operations autofs4_root_dentry_operations = {
224 d_revalidate: autofs4_root_revalidate,
225 d_release: autofs4_dentry_release,
226 };
227
228 /* For other dentries */
229 static struct dentry_operations autofs4_dentry_operations = {
230 d_revalidate: autofs4_revalidate,
231 d_release: autofs4_dentry_release,
232 };
233
234 /* Lookups in non-root dirs never find anything - if it's there, it's
235 already in the dcache */
236 static struct dentry *autofs4_dir_lookup(struct inode *dir, struct dentry *dentry)
237 {
238 #if 0
239 DPRINTK(("autofs_dir_lookup: ignoring lookup of %.*s/%.*s\n",
240 dentry->d_parent->d_name.len, dentry->d_parent->d_name.name,
241 dentry->d_name.len, dentry->d_name.name));
242 #endif
243
244 dentry->d_fsdata = NULL;
245 d_add(dentry, NULL);
246 return NULL;
247 }
248
249 /* Lookups in the root directory */
250 static struct dentry *autofs4_root_lookup(struct inode *dir, struct dentry *dentry)
251 {
252 struct autofs_sb_info *sbi;
253 int oz_mode;
254
255 DPRINTK(("autofs_root_lookup: name = %.*s\n",
256 dentry->d_name.len, dentry->d_name.name));
257
258 if (dentry->d_name.len > NAME_MAX)
259 return ERR_PTR(-ENAMETOOLONG);/* File name too long to exist */
260
261 sbi = autofs4_sbi(dir->i_sb);
262
263 oz_mode = autofs4_oz_mode(sbi);
264 DPRINTK(("autofs_lookup: pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d\n",
265 current->pid, current->pgrp, sbi->catatonic, oz_mode));
266
267 /*
268 * Mark the dentry incomplete, but add it. This is needed so
269 * that the VFS layer knows about the dentry, and we can count
270 * on catching any lookups through the revalidate.
271 *
272 * Let all the hard work be done by the revalidate function that
273 * needs to be able to do this anyway..
274 *
275 * We need to do this before we release the directory semaphore.
276 */
277 dentry->d_op = &autofs4_root_dentry_operations;
278
279 if (!oz_mode)
280 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
281 dentry->d_fsdata = NULL;
282 d_add(dentry, NULL);
283
284 if (dentry->d_op && dentry->d_op->d_revalidate) {
285 up(&dir->i_sem);
286 (dentry->d_op->d_revalidate)(dentry, 0);
287 down(&dir->i_sem);
288 }
289
290 /*
291 * If we are still pending, check if we had to handle
292 * a signal. If so we can force a restart..
293 */
294 if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
295 if (signal_pending(current))
296 return ERR_PTR(-ERESTARTNOINTR);
297 }
298
299 /*
300 * If this dentry is unhashed, then we shouldn't honour this
301 * lookup even if the dentry is positive. Returning ENOENT here
302 * doesn't do the right thing for all system calls, but it should
303 * be OK for the operations we permit from an autofs.
304 */
305 if ( dentry->d_inode && d_unhashed(dentry) )
306 return ERR_PTR(-ENOENT);
307
308 return NULL;
309 }
310
311 static int autofs4_dir_symlink(struct inode *dir,
312 struct dentry *dentry,
313 const char *symname)
314 {
315 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
316 struct autofs_info *ino = autofs4_dentry_ino(dentry);
317 struct inode *inode;
318 char *cp;
319
320 DPRINTK(("autofs_dir_symlink: %s <- %.*s\n", symname,
321 dentry->d_name.len, dentry->d_name.name));
322
323 if (!autofs4_oz_mode(sbi))
324 return -EACCES;
325
326 ino = autofs4_init_ino(ino, sbi, S_IFLNK | 0555);
327 if (ino == NULL)
328 return -ENOSPC;
329
330 ino->size = strlen(symname);
331 ino->u.symlink = cp = kmalloc(ino->size + 1, GFP_KERNEL);
332
333 if (cp == NULL) {
334 kfree(ino);
335 return -ENOSPC;
336 }
337
338 strcpy(cp, symname);
339
340 inode = autofs4_get_inode(dir->i_sb, ino);
341 d_instantiate(dentry, inode);
342
343 if (dir == dir->i_sb->s_root->d_inode)
344 dentry->d_op = &autofs4_root_dentry_operations;
345 else
346 dentry->d_op = &autofs4_dentry_operations;
347
348 dentry->d_fsdata = ino;
349 ino->dentry = dget(dentry);
350 ino->inode = inode;
351
352 dir->i_mtime = CURRENT_TIME;
353
354 return 0;
355 }
356
357 /*
358 * NOTE!
359 *
360 * Normal filesystems would do a "d_delete()" to tell the VFS dcache
361 * that the file no longer exists. However, doing that means that the
362 * VFS layer can turn the dentry into a negative dentry. We don't want
363 * this, because since the unlink is probably the result of an expire.
364 * We simply d_drop it, which allows the dentry lookup to remount it
365 * if necessary.
366 *
367 * If a process is blocked on the dentry waiting for the expire to finish,
368 * it will invalidate the dentry and try to mount with a new one.
369 *
370 * Also see autofs_dir_rmdir()..
371 */
372 static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
373 {
374 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
375 struct autofs_info *ino = autofs4_dentry_ino(dentry);
376
377 /* This allows root to remove symlinks */
378 if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
379 return -EACCES;
380
381 dput(ino->dentry);
382
383 dentry->d_inode->i_size = 0;
384 dentry->d_inode->i_nlink = 0;
385
386 dir->i_mtime = CURRENT_TIME;
387
388 d_drop(dentry);
389
390 return 0;
391 }
392
393 static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
394 {
395 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
396 struct autofs_info *ino = autofs4_dentry_ino(dentry);
397
398 if (!autofs4_oz_mode(sbi))
399 return -EACCES;
400
401 spin_lock(&dcache_lock);
402 if (!list_empty(&dentry->d_subdirs)) {
403 spin_unlock(&dcache_lock);
404 return -ENOTEMPTY;
405 }
406 list_del_init(&dentry->d_hash);
407 spin_unlock(&dcache_lock);
408
409 dput(ino->dentry);
410
411 dentry->d_inode->i_size = 0;
412 dentry->d_inode->i_nlink = 0;
413
414 if (dir->i_nlink)
415 dir->i_nlink--;
416
417 return 0;
418 }
419
420
421
422 static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
423 {
424 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
425 struct autofs_info *ino = autofs4_dentry_ino(dentry);
426 struct inode *inode;
427
428 if ( !autofs4_oz_mode(sbi) )
429 return -EACCES;
430
431 DPRINTK(("autofs_dir_mkdir: dentry %p, creating %.*s\n",
432 dentry, dentry->d_name.len, dentry->d_name.name));
433
434 ino = autofs4_init_ino(ino, sbi, S_IFDIR | 0555);
435 if (ino == NULL)
436 return -ENOSPC;
437
438 inode = autofs4_get_inode(dir->i_sb, ino);
439 d_instantiate(dentry, inode);
440
441 if (dir == dir->i_sb->s_root->d_inode)
442 dentry->d_op = &autofs4_root_dentry_operations;
443 else
444 dentry->d_op = &autofs4_dentry_operations;
445
446 dentry->d_fsdata = ino;
447 ino->dentry = dget(dentry);
448 ino->inode = inode;
449 dir->i_nlink++;
450 dir->i_mtime = CURRENT_TIME;
451
452 return 0;
453 }
454
455 /* Get/set timeout ioctl() operation */
456 static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
457 unsigned long *p)
458 {
459 int rv;
460 unsigned long ntimeout;
461
462 if ( (rv = get_user(ntimeout, p)) ||
463 (rv = put_user(sbi->exp_timeout/HZ, p)) )
464 return rv;
465
466 if ( ntimeout > ULONG_MAX/HZ )
467 sbi->exp_timeout = 0;
468 else
469 sbi->exp_timeout = ntimeout * HZ;
470
471 return 0;
472 }
473
474 /* Return protocol version */
475 static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int *p)
476 {
477 return put_user(sbi->version, p);
478 }
479
480 /* Identify autofs_dentries - this is so we can tell if there's
481 an extra dentry refcount or not. We only hold a refcount on the
482 dentry if its non-negative (ie, d_inode != NULL)
483 */
484 int is_autofs4_dentry(struct dentry *dentry)
485 {
486 return dentry && dentry->d_inode &&
487 (dentry->d_op == &autofs4_root_dentry_operations ||
488 dentry->d_op == &autofs4_dentry_operations) &&
489 dentry->d_fsdata != NULL;
490 }
491
492 /*
493 * ioctl()'s on the root directory is the chief method for the daemon to
494 * generate kernel reactions
495 */
496 static int autofs4_root_ioctl(struct inode *inode, struct file *filp,
497 unsigned int cmd, unsigned long arg)
498 {
499 struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
500
501 DPRINTK(("autofs_ioctl: cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u\n",
502 cmd,arg,sbi,current->pgrp));
503
504 if ( _IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
505 _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT )
506 return -ENOTTY;
507
508 if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
509 return -EPERM;
510
511 switch(cmd) {
512 case AUTOFS_IOC_READY: /* Wait queue: go ahead and retry */
513 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
514 case AUTOFS_IOC_FAIL: /* Wait queue: fail with ENOENT */
515 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
516 case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
517 autofs4_catatonic_mode(sbi);
518 return 0;
519 case AUTOFS_IOC_PROTOVER: /* Get protocol version */
520 return autofs4_get_protover(sbi, (int *)arg);
521 case AUTOFS_IOC_SETTIMEOUT:
522 return autofs4_get_set_timeout(sbi,(unsigned long *)arg);
523
524 /* return a single thing to expire */
525 case AUTOFS_IOC_EXPIRE:
526 return autofs4_expire_run(inode->i_sb,filp->f_vfsmnt,sbi,
527 (struct autofs_packet_expire *)arg);
528 /* same as above, but can send multiple expires through pipe */
529 case AUTOFS_IOC_EXPIRE_MULTI:
530 return autofs4_expire_multi(inode->i_sb,filp->f_vfsmnt,sbi,
531 (int *)arg);
532
533 default:
534 return -ENOSYS;
535 }
536 }
537
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